1. Field of the Invention
The present invention relates to an iris recognition system, and more particularly, to an apparatus for focusing iris images of both eyes in an iris recognition system using both irises of both eyes, by which the iris images of the mutually distanced both eyes are approached to reduce the distance between the two iris images in obtaining the iris images.
Meanwhile, the invention can be applied to an iris recognition system of both eyes which extracts the iris images of the both eyes including both images of the both eyes and compares the extracted iris images of the both eyes to a previously registered image data base of both eye iris images to execute credibility judgment and authentication of a recognizee.
In particular, the invention relates to an apparatus for focusing iris images of both eyes which can focus the iris images of the both eyes adjacent using a reflector angled at a predetermined degree to narrow the distance between the both eyes in the acquired both eye iris images so that unnecessary image information can be reduced and iris information necessary for recognition can be acquired in a sufficient amount.
2. Description of the Related Art
As well known, conventional systems for security, guard and identity authentication include contacting or non-contacting card systems. Further, systems have been popularized for authenticating identity and allowing or rejecting entry into specific spaces or access to specific information through recognizing fingerprints or an iris of a person.
Among these, the iris recognition system has an advantage that more precise recognition can be obtained with a higher recognition rate over the fingerprints recognition. In the iris recognition system, a specific pattern is processed into data using an image processing technique from an iris image photographed by a video camera and then compared to pre-registered iris data in authenticating a person.
FIG. 1 shows a configuration of a general iris recognition system. The operation of the iris recognition system will be described in reference to FIG. 1 as follows.
When a user approaches the iris recognition system, a distance-measuring sensor 109 measures a distance from the user 109. The distance measured like this is sent to a control unit 105 via a driver 107 to judge if the measured distance is within an operational range that the system can be operated.
If the user is within the operational range, a control signal is sent to the driver 107 to prepare for extracting an iris image. The driver 107 sends an active signal to the outer indicator 108 to inform the user that the system is operating, and when the user accordingly places an eye at an optical axis of a camera 103 through an optical window 101, a cold mirror 102 shields visual light while allowing infrared light to pass therethrough. A region where an iris is supposed to be placed is indicated so that the user can confirm if the eye is placed at the optical axis of the camera 103.
Again, the control unit 105 accepts a value of the measured distance from the distance measuring sensor 109 to the user, and calculates zoom and focus values of the camera 103 using the measured distance to execute zoom-in/zoom-out and focusing control. Then, the control unit 105 regulates the intensity of an illuminating unit 106 via a driver 107 according to the measured distance, and then photographs the iris image via the camera 103. The photographed iris image is signal processed in a frame grabber 104 corresponding to iris image analysis, and the control unit 105 executes iris recognition using information of the processes iris image to determine if to authenticate the user.
In such an iris recognition system, performance thereof is determined by speed and precision of iris recognition.
However, when recognition is carried out using the iris of only one eye, the iris image for recognition should be obtained in a large size in order to acquire sufficient information with only one iris. Therefore, the video camera for iris recognition is required to have a considerable level of zooming and focusing functions, in which the iris image should be photographed in a sufficient size while the zooming function is used to adjust a focus. Also, since the iris of only one eye is used, an operation area of the user should be set adjacent to the lens in order to acquire a sufficient level of iris image, and focusing is difficult.
Due to such reasons, the conventional iris recognition system using the iris image of one eye has been required to allocate a number of components and algorithms for realizing an automatic focusing function.
Further, with regard to comparative search time for iris recognition, the degree of rotation of the iris is not known when the iris of only one eye is used so that a comparative search is executed considering rotation of the iris thereby consuming a long search time. This acts as a great obstacle in obtaining the iris recognition system in real time.
Therefore, those problems can be solved if iris images of both eyes can be used in executing user authentication.
In other words, when all the iris images of the both eyes are used at the same time, desired iris images can be obtained substantially without using the zooming function, and thus incurring an iris image acquiring apparatus to be simplified.
Further, the error rate can be lowered since authentication is obtained only if iris information from the both eyes are identical using all the irises of the both eyes, and the degree of rotation of the irises can be easily obtained allowing the comparative search time of information to be shortened since so that a basis can be provided for executing iris recognition substantially in real time.
In simultaneously using the iris images of the both eyes like this, unnecessary information or glabella information unnecessary for iris recognition is acquired between the iris images of the both eyes photographed by a CCD camera, and thus such information has been an obstruction in processing iris information which is necessary in practice.
According to an aspect of the invention, it is provided an apparatus for focusing iris images of both eyes in a system which executes iris recognition by using the iris images of the both eyes of a user, the apparatus comprising: iris image focusing means for converting an incident path, whereby the distance between the iris images of the both eyes is narrowed on an optical path along which eye images of the user are focused to a camera. In the apparatus of the invention, the focusing means is an angled reflector with one side being inclined at an angle about the center.
According to another aspect of the invention, it is provided an apparatus for focusing iris images of both eyes comprising: a reflector inclined at an angle about a reference position for setting the iris images of the both eyes with reflection angles different with each other when the iris images of the both eyes are inputted; a lens for refracting the iris images reflected from the reflector; and a photographing device for converting optical signals containing the iris images into electric signals.
According to other aspect of the invention it is provided a method for recognizing iris images of both eyes comprising the following step of: reflecting lights inputted as the iris images of the both eyes in different angles for being narrowed, wherein all of the iris images of the both eyes are used in user authentication through focusing, photographing and authentication, whereby the distance between the iris images of the both eyes formed on a photographing device is narrowed.
According to the invention, in the iris recognition system using the both eyes, the distance between the two eyes or the distance between the iris images formed on the photographing device can be reduced so that the iris images can be acquired larger and more precise.